Liquid dishwasher detergent compositions, both aqueous and nonaqueous, have achieved commercial popularity for use in household automatic dishwashers. Representative of such detergent compositions are the automatic dishwasher compositions disclosed in U.S. Pat. Nos. 5,209,863; 5,219,486; 5,225,096; 5,246,615; 5,252,241; and 5,252,242, the disclosures of which are herein incorporated by reference.
These compositions, however, are not useful for institutional and industrial cleaning, which are characterized by short wash cycles and both low and high temperatures. The low concentrations of caustic alkali and, when present, chlorine bleach make the household products ineffective for institutional and industrial applications. Moreover, sodium silicate, a key ingredient in household products to inhibit corrosion, is not generally used in institutional and industrial products for machines having very short wash cycles as it tends to leave a cloudy film on wares and machines over time.
Furthermore, products which are used in institutional and industrial cleaning applications have their own particular disadvantages. For example, solid brick detergent compositions, such as those disclosed in U.S. Pat. Nos. 4,569,780; 4,569,781; 4,753,755; 4,808,236; 4,846,989; and 5,080,819, the disclosures of which are herein incorporated by reference, are all solid blocks which must be predissolved with hot water before they can be pumped into a warewash machine. Considering the very short wash times employed with these machines, e.g., &lt;1 minute, performance is compromised when a portion of the wash cycle is devoted to dissolving the detergent and pumping it into the machine.
Similarly, the solid paste composition disclosed in U.S. Pat. No. 5,019,290, the disclosure of which is herein incorporated by reference, is very thick and cannot be pumped. Accordingly, as with the solid brick products, the desired amount of detergent must be dissolved with hot water and then transferred into the machine.
The liquid emulsion product disclosed in U.S. Pat. No. 4,512,908, the disclosure of which is herein incorporated by reference, is a low viscosity, pumpable, non-concentrated liquid containing a clay thickener. The long term stability of this product is uncertain.
There is, therefore, a need in the art for a stable concentrated liquid gel warewash which is predissolved and dispensable through a metered device and has high level of caustic alkali and other active ingredients for use in institutional and industrial cleaning applications.